The document US 2014/0021894 A1 discloses a torque ripple reduction of multiple harmonic components, wherein a ripple reduction signal is generated in response to the torque command that simultaneously cancels a first and a second ripple harmonic in the torque signal.
EP 2 043 255 A2 discloses a system and method for controlling torque ripples in synchronous machines, wherein power and/or torque control signals are provided to the power converter to regulate the fundamental power and/or torque produced by the machine.
EP 2 485 388 A1 discloses a method for controlling the operation of an electromechanical transducer, wherein a harmonic control signal is determined being indicative for a harmonic operational behavior of the electromechanical transducer, wherein the harmonic operational behavior is given by electric and/or mechanical oscillations having frequency components being different from a fundamental frequency. Further, a modified drive signal based on the determined harmonic control signal is generated and supplied to electromagnetic coils of a stator of the electromechanical transducer.
Reduction of noise and vibration may be a common concern in high performance applications employing permanent magnet machines, namely wind turbines using high power permanent magnet synchronous generators in which spatial harmonics of inductance and magnet flux may lead to high torque ripple.
Conventionally, this problem may be approached in the machine design phase. However, due to manufacturing limitations, a noise/vibration-free machine may not be possible to be manufactured. Thus, control strategies and solutions are mandatory in order to comply with noise/vibration requirements.
In the aforementioned prior art documents, the manipulation of torque or Iq command may commonly be used in a torque ripple control. However, those techniques may require a high bandwidth of the torque or current control system which may be difficult to be achieved in high power applications. Alternatively, voltage harmonics may be injected in a conventional system, directly into the command voltage for PWM modulation generation allowing for extended bandwidth.
It has been observed, that vibration and/or noise of an electrical or mechanical component of the wind turbine is not reduced in a sufficient manner or to a sufficient degree in conventional systems. Thus, there may be a need for an arrangement for appropriately controlling a wind turbine, such that noise/oscillations are effectively reduced during operation. Furthermore, in order to construct such a control arrangement, there may be a need for an arrangement for determining in particular a d-component of a reference current in a d-q coordinate system which may eventually be used within the control arrangement, in particular in a generator side controller for controlling a generator side frequency converter of a wind turbine.